- “My choice that year was a complicated one, and in many ways irrational. It was as if I was bedevilled….
Later, I wanted to understand if it was really because of your summons….„
Han Shan is a recurring character in I Shall Seal the Heavens, whose appearances, although few and far in between, are always of marked importance.
An azure-robed middle-aged Immortal who is defined as possessing a heroic aura and having a majestic appearance.
He is thoroughly devoted to his wife Xue'er, supported by his actions in the Realm of Bridge Ruins. He is the kind of person who would never forget an act of kindness.
He is a clone of the Frost Soil Demon Emperor. During the war of the Demon Immortal Sect with the Ji Clan 10,000 years ago, he was able to evade the Ji Clan's ancestor and thereupon lived in the mortal world for countless generations. After completing his Solitary Sword Song, his memories as the Frost Soil Demon Emperor came rushing back.
Prior to Book 4
In the past, to cultivate his Solitary Sword Song, Han Shan prostrated himself before the Soul of the Bridge of Immortal Treading to gain limitless life force and eternal life. In return he promised to exercise his faith upon the Bridge Soul and become one of the Bridge Slaves.
But Xue'er, his wife, to ensure that he never would, became a Bridge Slave in his place and became the successor to the Bridge Soul. 
Meng Hao first encountered him in the Realm of the Bridge Ruins, drinking from an alcohol flagon from time to time. Seeing Meng Hao, Han Shan approached him and upon having ascertained that the former's destination is the same as his, traveled together with him for months.
As a payment for Meng Hao's goodwill, he bestowed an Alcohol Core which fused with Meng Hao's Gold Core. This Alcohol Core will enable Meng Hao to wield Han Shan's Dancing Sword Qi twice, which can slay anyone under the Immortal realm.
It was made known that for three thousand years, he traveled twenty-thousand worlds, searched through multitudes of Bridge Slaves, all in search for his wife. Trying to get the Soul of the Bridge of Immortality to return his wife, he attacked the palace the spirit was located in. This induced the said spirit, who is also called the Bridge Soul, to come out.
The spirit, or soul, appeared before Han Shan and claimed that should Han Shan be able to kill all the Bridge Slaves in that area in the space of one hundred breaths, his wife will show herself to him Upon hearing this, he proceeded to accomplish the deed. Shortly thereafter, the slaughtered Bridge Slaves reappeared with not a single injury on their bodies. 
When Han Shan finally found Xue'er, his wife was on the verge of becoming the new Bridge Soul and thus only had a few moments of lucidity. She then begged for him to kill her in order to be released. But Han Shan, who so loved his wife, was unable to lay a hand on her. He then decided to become a Bridge Slave to accompany his wife, who by then, had truly become the new soul of the Bridge of Immortal Treading.
Before becoming one, he decided to bestow upon Meng Hao his legacy, his sword and even his alcohol flagon. He then had Meng Hao promise that should he become powerful enough, to rescue him and his wife from their situation. 
Rather than becoming soulless like the rest of the other Bridge Slaves, Han Shan decided to used his power as the Frost Soil Demon Emperor to seal himself and his wife and wait for the day of their awakening.
True to his word, after having ascended and subsequently earning a place in the Echelon, Meng Hao returned to the ruins of the Bridge of Immortal Treading to repay Han Shan's kindness. Meng Hao decided to subdue the bridge using his Paragon Bridge, using the latter to absorb the Bridge of Immortality.  After freeing the two, Meng Hao gave them identity medallions and suggested them to settle down in Planet South Heaven. As Han Shan doesn't really mind going anywhere, he readily agreed to the idea.
- He was first mentioned as a clone of the Frost Soil Demon Emperor, but then was later considered a reincarnation.